1. Field of the Invention
The present invention relates to a method of executing a calibration process in accordance with a characteristic of an image formation unit.
2. Related Background Art
For example, in a case where image data synthesized by a personal computer are output by a printer, brightness signals of R (red), G (green) and B (blue) composing the above image data have to be color-converted into color signals of Y (yellow), M (magenta) and C (cyan), and further of K (black) if necessary. In such the color conversion, a relationship in general between an input color space based on the brightness signals and an output color space based on the color signals is nonlinear. Therefore, in the data conversion, if the correspondence between the input data and the output data is nonlinear as above, it is not easy to create an exact model of such the conversion and perform calculation based on the created model. Further, even if a certain model of the conversion can be created, a calculation amount required in this conversion might become enormous. Therefore, to solve such a problem of the data conversion, there has been known a method of easily performing data conversion by previously creating an LUT (look-up table) of which the output data respectively correspond to the input data.
Incidentally, the previously obtained LUT is only different in each printing mode, whereby the same kind of printers always use the same LUT regardless of conditions based on heads, printers and the like.
However, even if the previously created LUT is used, the optimum printed result is not always obtained due to individual differences of the printer main bodies, the ink heads and the like. For example, if magenta is set to be intense on the LUT, the image obtained by using this LUT becomes reddish as a whole, whereby a gray balance might not be able to be maintained.